Packages that are sent from a sender to a receiver will require opening by the receiver. Many packages come with a flap that can be folded over to seal the package opening. Packages with flaps or other closures require a way of sealing the package and a way of opening the sealed package. Both sender and receiver have concerns regarding the integrity of the package during transit. Both sender and receiver are motivated to have a robust seal that will resist tearing or opening. Robust seals are typically achieved with an adhesive on the flap that bonds to the container. Lifting the flap that has been bonded to the container with an adhesive is, however, a difficult task. Accordingly, there have been many proposals for facilitating the opening of sealed packages that rely on the tearing of the flap that seals the package. Such proposals mainly rely on the use of perforations, strings, and tear strips.
The considerations for deciding which mechanism to utilize for opening packages are related to the construction materials of the package, the materials' tear properties, the complexity of manufacturing, and the associated costs.
Some users may prefer packages with robust opening mechanisms above all else, while other users may prefer the easier opening mechanisms that are nevertheless reliable enough to withstand typical handling while in transit.
While the advantages of robust opening mechanisms are evident, many of these packages involve complex or intricate manufacturing processes leading to higher prices which the consumer is less willing to accept. Examples may include strings and tear strips that are made from materials different to the flap or closure material. Strings and tear strips function by either being embedded within the flap material or by being directly adjacent to the flap, so that pulling on the string or tear strip will cause cutting or tearing of or through the flap material. Because strings and tear strips are external devices that must be integrated into the flap, manufacturing complexity is introduced.
A simpler, but more prone to inadvertent opening, is an opening mechanism that is made from the flap material itself. Perforations that completely penetrate the flap material are made along two rows to weaken the flap material along a specified narrow strip of material. It is generally regarded that such opening mechanism will sacrifice package integrity. This is because the flap is, in essence, connected to the remainder of the envelope with perhaps only as much as half of the flap material between the perforations. Furthermore, because the perforations will be visible and exposed in the exterior side of the flap, the perforations are likely starting points where, if enough pressure is applied by an object, a tear might ensue.
Accordingly, there is a need to provide an opening mechanism that given a robust seal will nevertheless be easy to open, but will be less likely to open inadvertently.